1. Field of the Invention
The present invention relates to a technique of stock management for consumables used in an image formation apparatus.
2. Description of the Related Art
A conventional consumables stock management system applies a stock subtraction operation to consumables using a notification indicating that there is a low residual amount (toner low notification) or no residual amount (toner empty notification) of a recording material (toner, ink or the like) that is a consumable. The above notification is hereinafter referred to as residual amount notification.
However, a method which detects a residual amount of a recording material in a printing apparatus may generate signals indicating a low residual amount in the printing apparatus which exceed a notification threshold by a plurality of times, around the time when the residual amount of recording material reaches the notification threshold. Consequently if a unit stock subtraction operation for a consumable is performed by a management apparatus corresponding to individual residual amount notification signals, accurate consumables stock management can not always be conducted.
For example, printing in an image formation apparatus to which a cartridge supplies consumables may be recommenced by a user removing the cartridge from the print apparatus and shaking the cartridge. In this case, a plurality of low residual amount signals is produced in the apparatus in a short period. Namely, a plurality of residual amount signals is output for a single cartridge (consumable). Consequently the problem arises that accurate stock management is not achieved.
Japanese Patent Application Publication No. 2003-159854 is proposed to solve the above problem. Publication No. 2003-159854 discusses a method by which, based on the number of sheets printed, a stock subtraction operation is not performed when the number of printed sheets is lower than a predetermined number in the interval from the production of a signal to the production of an immediately subsequent signal, or when a notification is received within a predetermined time period.
However while the above conventional method avoids erroneous detection, it entails the following problem which will be discussed below using an example of toner as a recording material.
When color toner having a plurality of specific output patterns is used, a certain output pattern may result in a large deviation in the actual toner consumption amount and the printed number of pages.
For example, a glossy finish similar to a photograph may be produced by applying transparent clear toner to a sheet of paper such as a color print. Printing operations using clear toner may apply clear toner to the whole sheet surface to form an output pattern, which consumes a large amount of clear toner in a single operation (whole surface printing). There are also output patterns producing a glossy finish for images in which a print product is produced using different toner and clear toner printing is only partially applied to the images in the print product.
Partial output patterns also use clear toner to print letters and data (for example, company logos) which are registered in a predetermined form like watermarks.
When using whole surface printing as discussed above, while a counter is incremented by a value of “1” with respect to a single printing operation for a single page, an amount of toner consumption is high, which corresponds to several pages in comparison to other partial printing methods. In other words, application of a normal counter setting when using whole surface printing does not keep pace with the relationship between toner consumption amount and print operations using other output patterns. Consequently when a counter value corresponding to a number of printed sheets is measured in a conventional manner using color information (color/monochrome), the conventional relationship between the counter number and the actual toner consumption amount does not hold with respect to clear toner.
Conventional determination methods entail the following problems when they are applied to an apparatus realizing a plurality of output patterns in which there is a wide variation in the used amount of recording material of a specific color.
For example, when printing operations are performed biased toward a specific use, there is a considerable difference between the actual consumption amount and the measured consumption amount represented by the counter value as to the number of printed pages.
As discussed above, a predetermined value may be provided with reference to a number of sheets which can be printed between signals, to thereby detect erroneous notification. The predetermined value is set based on the printable number of sheets predetermined for each consumable. For example, the value “ 1/10” for a printable sheet number may be set as the predetermined number.
In this regard, repetition of solid printing (whole surface printing) may be performed or printing may be performed in which several times the amount of recording material is consumed in comparison with other output patterns and the actual recording material in the consumable is consumed and runs out even when a low number of pages are printed. Further, a user may repeat printing with an output pattern which consumes a low amount of toner, or may carry out a plurality of different output patterns. Thus, conventional methods entail the risk that a correct residual amount notification may be determined to be an erroneous notification, thereby resulting in erroneous control such as incorrect stock subtraction and suitable stock management cannot be conducted.